1. Field of the Invention
The present invention relates to disk drives for computer systems. More particularly, the present invention relates to a disk drive comprising a support member for supporting a flex circuit and having a restraining member for vertically restraining an inertial latch.
2. Description of the Prior Art
A computer system usually includes one or more disk drives for economical, non-volatile data storage. Prior art disk drives typically comprise a base for housing a disk and a head attached to a distal end of an actuator arm. A spindle motor rotates the disk about its axis, and a voice coil motor (VCM) rotates the actuator arm about a pivot in order to position the head radially over the disk. A crash stop is provided which facilitates latching the head in a park position while the disk drive is powered down in order to protect the data recorded on the disk as well as prevent damage to the head. The head may be parked on a landing zone on the inner diameter (ID) of the disk, or alternatively, the head may be parked on a ramp located at the periphery of the disk (a.k.a., ramp loading/unloading).
The actuator arm comprises a tang attached to a base end and positioned between a first arm and second arm of the crash stop. The second arm presents-a physical barrier to the tang so as to limit the stroke of the actuator arm, thereby preventing the head from exceeding a radial limit (e.g., the edge of the disk). The first arm comprises a parking latch with a magnet for latching the tang to the first arm, thereby safely parking the head (e.g., on the inner diameter of the disk). In order to prevent damaging the head as well as the surface of the disk, the force from the magnetic parking latch helps prevent the actuator arm from unlatching when the disk drive is subjected to an external, physical shock. However, the actuator arm will unlatch if the physical shock is of sufficient magnitude, particularly if the physical shock causes the disk drive to rotate such that the magnetic parking latch is jerked away from the tang.
In prior art disk drives an inertial latch has been employed which prevents the actuator arm from unlatching when the disk drive is subjected to large rotational shocks. The inertial latch comprises a protruding arm which rotates about a pivot and xe2x80x9ccatchesxe2x80x9d the actuator arm to prevent it from unlatching during a rotational shock. The inertial latch also comprises a biasing mechanism for applying a biasing force to the arm in order to reposition it when the rotational shock subsides. Prior art inertial latches employ a torsion spring comprised of a wound coil which provides resistance to torque, thereby providing the biasing force against the rotation of the arm. However, torsion springs are complicated and expensive to manufacture, and their spring characteristics (e.g., spring constant) are sensitive to dimensional tolerances. Further, installing the torsion spring is difficult and requires a high degree of accuracy which further increases the cost and manufacturing complexity of the inertial latch.
Another problem with prior art torsion springs is the linear relationship between the displacement of the spring versus the load as illustrated in FIG. 6A. Because the relationship is substantially linear, it is difficult to design the torsion spring so that the inertial latch operates properly when the disk drive is subjected to small rotational shocks. Thus, the magnetic parking latch within the crash stop is typically designed to withstand larger rotational shocks than would be necessary if the spring load curve of the inertial latch were more constant. Designing the magnetic parking latch with a higher latching force to compensate for the insensitivity of a torsion spring further increases the cost of the disk drive.
There is, therefore, a need for a disk drive employing an improved inertial latch that is more cost-effective to manufacture and install, and more sensitive to small physical shocks.
The present invention may be regarded as a disk drive comprising a disk, an actuator arm, a head attached to a distal end of the actuator arm, a voice coil motor for rotating the actuator arm to position the head radially over the disk, and a flex circuit having a first end and a second end, the first end coupled to the actuator arm. The disk drive further comprises a parking latch for latching the actuator arm in a latched position in order to park the head during a non-operating mode, and an inertial latch for maintaining the actuator arm in the latched position when the disk drive is subjected to a physical shock. The inertial latch comprises a body having a protruding arm and defining a pivot axis. The inertial latch further comprises a support member coupled to the base, the support member comprising a connecting surface for connecting to the second end of the flex circuit, and a restraining member connected to the body of the inertial latch proximate the pivot axis, wherein the restraining member vertically restrains the inertial latch.
In one embodiment, the disk drive further comprises a post comprising a curved side surface and a top surface. The inertial latch further comprises a cylindrical cavity, an interior pivot surface defined by an interior surface of the cylindrical cavity, and an exterior pivot surface defined by an exterior surface of the cylindrical cavity opposite the interior pivot surface. The post is disposed axially through the cylindrical cavity such that the top surface of the post contacts the interior pivot surface of the cylindrical cavity, and the restraining member contacts the exterior pivot surface of the inertial latch.